Variable condenser



Jan.12,1932 W DU.L,ER 1,841,095

VARIABLE CONDENSER Original Filed Feb. 14, 1924 3&1 w my M Patented Jan. 12, 1932 UNITED STATES VPATENT OFFICE WILLIAM DUBILIER, OF NEW ROCHELLE, NEW YORK, ASSIGNOR TO DUBILIER CONDENSER CORPORATION, 0F NEW YORK, N. Y., A CORPORATION 0F DELAWARE VARIABLE CONDENSER Original application led Februaryv 14, 1924,..Scr1a1 No. 692,864. Divided and this application illed 4February 2,

My invention relates to condensers, and

more particularly to variable condensers of the type used in radio communication.

This application is a division lof my ap- -5' plication, Serial No. 692,864, filed February 14, 1924 which has matured into Patent An object of my invention is to provide a condenser in which gradual adjustments of 10 capacity may be effected with facility and vide a condenser structure in which the fixed v elements are attached to the support in a simple and extremely sturdy manner, wherebythe condenser maybe subjected to long continued use without fear of injury to the fixed elements.

A still further object of my invention is to provide means for effectively preventing displacement of the fiexible element in the operation of the condenser, and also to provide a structure in which the movement of the compression plate for operating the resilient element is llimited.

With these and other objects in view which may be incident to my improvements, the invention consists in ;the parts and combina'- tions to be hereinafter set forth andy claimed. with the understanding that the several necessary elements comprising my invention, may be varied in construction, proportions and arrangement, without departing from the spirit and scope of the appended claims.

In order to make my invention more clearly understood, I have shown in the accompanying drawings means for carrying the same into practical effect, without limiting the improvements in their useful applications to the particular constructions, which for the purpose of explanation, have been made the subject of4 illustration.

Serial No. I6,375.

In the drawings:

Figure l is a top plan view of my variable condenser;

Fig. .2 is a longitudinal sectional view taken on the line 2 2 of Fig. 1, looking in' the direction ofthe arrows;

Fig. 3 is a detail cross sectional yview taken,

on the line 3,-3 of Fig. 1, looking in the direction of the arrows. In my invention, the fixed elements comprise adjacent sheets of metallic foil insulated from each other, and fixed to a suitable insulating support. The sheets of metallic foil are covered by aninsulating-sheet of mica which extends beyond the edges of the adjacent sheets of foil, forming a rejecting overlapping insulating sheet, which prevents possible injury tothe edges' of the foil.

The adjacent sheets of metalliefoil and the mica sheet are held to the support b means of eyelets which are passed through the support, the metallic foil, and the insulating sheet of mica, and are riveted in place to maintain holding washers in firm contact with'the mica sheet. The resilient movable .F

element of the condenser comprises a bow, or U-shaped metal strip whose center is adapted to contact against the insulating mica sheet covering the fixed elements. A guiding yoke is attached to the support for the fixed elements, and prevents displacement of the movable element of the condenser. The movable element has no electrical contact with lthe terminals of the condenser, and the adjacent sheets of metallic foil have no direct electrical connection with each other or with the resilient movable element.

Within the yoke is adapted to move a compressionplate against which the ends of the movable element bear. A reciprocable shaft operated by the movement of a screw within an operating knob causes the compression plate to approach or recede from the fixed ing support 1 of bakelite or someiother suitable insulating material. Fixed to the support 1 at its under side, by some suitable adhesive, are adjacent strips of metallic foil 2 in alinement, and overlying the strips of metallic foil 2, which have no direct electrical connection with each other, is an insulating sheet of mica 3 whose edges project beyond the edges of the strips of foil to protect it from injury (see Figs. 2 and 3). Passing through the support 1, the adjacent strips of metallic foil 2 and the insulating sheet of mica 3 are eyelets 4. The eyelets 4 are inserted through the various layers and holding washers 5 are slipped over the eyelets so that when the eyelets are riveted in place, the holding washers 5 firmly hold the mica sheet 3, which is preferably also adhesively attached to the adjacent strips 2 of metallic foil, against the metallic foil, and the whole against the support 1.

The foil of each element adjacent the eyelets 4 is brought into close electrical contact with the eyelets 4 by turning down sections 2 of the adjacent sheets of foil 2 to contact with the respective eyelets. The washers' that hold the condenser elements firmly in place 0n the supports 1 also serve to tightly hold the adjacent strips of foil in contact with the eyelets. The adjacent strips of metallic foil 2 and the mica sheet 3 comprise the fixed elements of my condenser.

Fastened to the support 1 by means of screws 6, is a yoke 7 of insulating material having downwardly depending parallel sides 8, which project below the fixed element of the condenser. The yoke 7 is formed with a "protruding central support 9. The sides 8 have cut out portions 11 therein, which lightens the construction. Passing through the depending parallel sides 8 are stop bars 12, comprising bolts which pass through from one side to the other, and are held in place'by means of nuts 13. The stop bars 12 act to limit the movement of the movable element of the condenser in its minimum setting, as will be hereinafter explained.

Adapted to contact at substantially'its middle point against the insulating mica sheet 3 covering the adjacent fixed elements 2 of the condenser, is a flexible resilient me tallic strip 14, of U, or bow shape. rlhe free ends 15 of the strip 14 bear against and are adapted to slide upon a metallic compression plate 16, which is affixed at substantially its middle by means of a screw 17 to a reciprocable shaft 18. Downward movement of the compression plate 16 is limited by the stop bars 12.

The reciprocable shaft 18 passes through an aperture 19 formed in theresilient metallic' strip 14 that operates as the movable element my condenser. There is an open' ing 21 formed in the mica strip 3 covering the adjacent fixed elements. and the inner `Leijacent edges of the fixed elements are spaced well back from the edges of the open" ing 21 and out of contact with the shaft 18. The reciprocating shaft 18 passes through an opening 22 formed in the support 1, and an opening 23 formed in the support 9 of the oke 7.

y The support 9 is provided with. an annular flange 24. Lying on top of this annular fiange 24 is a metallic washer 25 which is depressed at 26 into a depression formed in the upper surface of the support 9. This prevents the washer 25 from rotating. The washer 25 is provided with a tab or lug 27 which fits into a slot 27 formed within the shaft 18 (see dotted lines Fig. 1). The tab 27, by reason of its engaging the slot 27 in the shaft 18, prevents possible rotation of the shaft 18.

Mounted over the support 9 and having its lower surface contacting with the washer 25 is an operating knob 28 of insulating material. The knob 28 is provided with an inner metallic hollow member 29 which is keyed to, or fitted tightly into, the operating knob 28, and is adapted to rotate with the knob. The metallic hollow member 29 is provided with internal screw-threads 31 engaging with screw-threads 32 formed on the recipro eating shaft 18. To hold the operating knob in operative position, I have provided a U- shaped holding piece 33 of resilient metal, which engages the flange 24 formed on the upper end of the support 9, and likewise engages a flange 34 formed on the lower end of the operating knob 28.

The U-shaped holding piece 33 holds the operating knob in operative position. To hold the U-shaped holding piece 33 in place after being fitted over the flanges 24 and 34, I have provided a bolt 35 which passes through the free ends 36. A nut 37 holds the bolt in place and prevents the U-shaped holding member 33 from slipping from the fianges 24 and 34, though it is to be understood that the holding member is not so tightly adjusted as to prevent free rotation of the operating knob 28.

Upon turning the operating knob 28, the screw-threads 31 engage with the screwthreads 32 of the reciprocating shaft 18 and feed the shaft either in an upward or downward direction. The tab 27 on the washer 25, by engaging with the slot 27', prevents ppssible rotation of the reciprocating shaft ln operation, by turning the operating,

connectionl between the adjacent fixed elements of the condenser.- As the flexible element 14 comes more and more into contact with the mica sheet 3, the capacity of the device is caused to increase. As the flexible element is picked up from contact with the mica ksheet 3, the bridging effect becomes minimized and the capacity of the device falls.

While I have shown and described the preferred embodimentof my invention, I wish it to be understood that I do not confine myself to the precise details of construction herein set forth, by way of illustration, as it is apparent that-many changes and variations may be made therein, by those skilled in the art, Without departingfrom the spirit of the invention, or exceeding the scope of the appended claims.

I claim l. In a variable'condenser, an insulating support, adjacent elements each comprising a metallic strip mounted on the support, an insulating sheet over both metallic strips, eyelets passing throu h the support, the metallic strips and the insulating sheet, and in electrical contact with the metallic stri s, and a flexible movable element adapted to e laid down on and picked up from the surface of the insulating sheet, whereby the capacity of the device may be varied.

2. In ava-riable condenser, an insulating support, adjacent elements each comprising a sheet of ymetallic foil mounted on the support, an insulating sheet of mica over the said sheets of metallic. foil, eyelets passing throulgh the support, the metallic sheet foil and the mica sheet and in electrical connection with Athe metallic 4sheet foil, and a resilient movable metallic strip adapted to be laid down on and picked up from the surface of the mica sheet, whereby the capacity of the device may be varied.

3. A variable condenser comprising adja cent fixed elements, a resilient movable element insulated from the fixed elements, a reciprocable shaft having screw-threads thereon, means operated by the shaftto flex the resilient element to vary the capacity of the condenser, an operating knob, and screwthreaded means .on the knob to cooperate with the screwthreads on the shaft to reciprocate the shaft. ,Y

4. A variable condenser comprising a support,',adjacent1fixed condenser elements mounted thereon, a U^shaped resilient movable element, a compression plate on which the ends of the movable element bear, a reciprocableshaft passing through the support andattached to the compression plate, screwmeans to reciprocate the shaft, a guiding yoke for the movable element fitting over the support and the fixed elements, and means carried by the guiding yoke for limiting the able element, and means to limit the` movement of the movable element.

6. A variable condenser comprising ad'acent fixed elements in alignment, a Inova le element adapted to bridge the fixed elements and to move in a lateral direction relative to the fixed elements to vary `the capacity ofthe condenser, and terminals connected to the fixed elements to connect the condenser in circuit.

7 A variable condenser comprising adjacent fixed elements, a. fiexible movable eement bridging the fixed elements and adapted to be flexed in such manner as to vary the capacity of the. condenser, and terminals connected to the fixed elements to connect the condenser in circuit.

8. A variable condenser comprising adj acent fixed elements, a resilient movable member, a compression late, a yoke for guiding the movable mem er, means to flex the resllient movable member to bridge the adjacent elements, and terminals connected to the fixed elements to connect the condenser in circuit. I

9. A variable condenser comprising adjacent fixed elements in alignment, terminals connected to the fixed elements to connect the condenser in circuit, and an element insulated from the fixed elements and movable toward and from 4the fixed elements to vary i the capacity of the condenser.

10. A variable condenser comprising adj acent fixed elements insulated from each other, a movable element insulated from the fixed elements, means for causing the movable element to be laid down on and picked up from the fixed elements to vary the capacity, and terminals connected to the fixed elements to connect the condenser in circuit.

11. A variable condenser comprising adj acent fixed elements insulated from each other,

a movable element insulated from the fixedA elements, a reciprocable shaft for moving the 13. A variable condenser comprising a. supporting member of insulation, adjacent elements 1n alignment 4secured thereto, a bowed flexible movable element having part 5 of its surface spaced from the ixed elements and part in proximity thereto and ada ted to be bent to vary the portion ofits sur ace in proximity to the fixed elements, so that the capacity of the condenser can be varied, and

10 terminals connected to the `fixed elements to connect the condenser in circuit.

14. A condenser comprising two fixed spaced plates in a common plane, separate circuit terminals for said plates a third plate 15 movable toward and from said spaced plates; and a layer of dielectric material between said third plate and said two spaced plates, and means for pressing said `elements together to vary the' distance betweenthem.

20 igned at New York in the county of'New York and State of New York this`31st day of u January, A. D. 1925. fy WILLIAM DUBILIER. 

